Currently, there are two existing solutions to connect a client layer Network Management System (NMS) to a remote packet network island which are separated by an optical network.
In a first solution, an out-of-band data communication network (DCN) is needed to let the NMS possess enough information about a remote edge node, in order to initiate the setup of an optical connection, e.g. between an edge node to which the NMS is connected and the remote edge node of the remote packet network island. In this respect, “out-of-band” may relate to the fact that the DCN might not share physical links with the optical network via which communication may be enabled. According to this solution an out-of-band data communication network is required. The out-of-band DCN requires a complete network to be maintained in parallel, at least temporarily at times when there is no optical connection between the edge node and the remote edge node.
In a second solution, the edge nodes are connected by means of an in-band DCN connection over an already established optical connection. The already established optical connection keeps the client layer NMS connected to one or more packet network islands. According to this solution only an already established optical connection can be used.